The recruitment of inflammatory cells, including macrophages and neutrophils, is appreciated as an important part of wound healing. Altered levels of neutrophils and/or macrophages have been described in many circumstances of impaired wound healing, including aging, diabetes, and systemic infection. The broad, long-term objective of this proposal is to understand how leukocyte recruitment into sites of injury is regulated. The hypothesis of this application is that the temporal and spatial regulation of leukocyte recruitment is critical to optimal wound healing. Our previous studies have shown that leukocyte infiltration into healing wounds is governed by the production of a family of related leukocyte chemoattractant cytokines, termed chemokines. Specific Aim 1 employs a well-characterized murine model of excisional wound healing to define the expression patterns of 40 to 60 known members of the chemokine network. Limited microarray analysis will be used to correlate the expression of clusters of chemokines with the characterized pattern of inflammation in this wound model. This data will be utilized in Specific Aim 2, which will determine the essential and specific roles of designated chemokines in wound healing. The importance of the identified chemokines to the recruitment of neutrophils and macrophages will be examined utilizing neutralizing antibodies. Additional experiments will discover if alterations in the expression of chemokines play a role in impaired healing, such as aging. Since the importance of neutrophil recruitment to the repair of wounds is only minimally understood, Specific Aim 3 will test the hypothesis that proper neutrophil infiltration influences the healing process. Chemokine production, inflammation, and proliferative processes will be compared in wounds of neutropenic and normal mice. Overall, the results will provide novel information regarding 1) chemokine production and inflammatory cell recruitment in wounds, and 2) the role of aberrant wound inflammation in impaired wound healing. The proposed studies are applicable not only to wound healing, but more generally to the acute inflamnmatory response. This knowledge may suggest new therapeutic approaches for situations of pathologic inflammation and aberrant wound repair.